ABSTRACT NUMBER: ESOC2026A2310 REDEFINING ACUTE SYMPTOMATIC SEIZURES: TIMING-BASED RECURRENCE RISK THRESHOLDS AFTER STROKE

Abstract Background and aims The 7-day cut-off for acute symptomatic post-stroke seizures presumes recurrence risk <60%, whereas later seizures are often treated as epilepsy (≥60%). We quantified recurrence risk by timing and evaluated data-driven cut-offs. Methods Individual participant data were pooled from 31 cohorts across ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, and a cerebral venous thrombosis consortium. Recurrence after the first post-stroke seizure was analysed with inverse-probability weighting for antiseizure medication treatment and Fine–Gray competing-risk regression (death). Ten-year cumulative incidence (95% CI) was estimated by stroke-to-first-seizure timing: 0–30 days, 1–3 months, 4–12 months, 13–24 months, and >2 years. Binary cut-offs were compared using BIC. Results Pooled etiologies (n=2,239): 10-year recurrence risk was 25% (22–28), 63% (43–76), 69% (60–76), 61% (45–72) and 49% (32–62), respectively. Versus 0–30 days, subdistribution hazard ratios (sHR) for 1–3 months, 4–12 months, 13–24 months and >2 years were 3.42 (2.12–5.51), 4.03 (3.02–5.39), 3.21 (2.14–4.81) and 2.33 (1.45–3.74); BIC favoured 28 days. Ischemic stroke (n=783): risks were 21% (15–25), 47% (19–65), 69% (58–77), 53% (33–67) and 38% (16–55); corresponding sHRs were 2.72 (1.26–5.86), 5.01 (3.26–7.69), 3.30 (1.84–5.93) and 2.10 (1.01–4.37); BIC favoured 33 days. Conclusions Recurrence risk is non-linear, with a mid-term peak and later decline, arguing against a universal 7-day boundary. A timing-informed acute/remote threshold near ~4 weeks better aligns with the ≥60% criterion; dynamic, etiology-aware rules are warranted. Conflict of interest Nicolas Gaspard reports institutional grant support from the Fonds de la Recherche Scientifique and Fonds Erasme pour le Recherche Médicale for the present work. Marian Galovic received fees and travel support from Arvelle, Advisis, Bial and Nestlé Health Science outside the submitted work. Laura Abraira has received personal fees and travel support from UCB Pharma, Eisai, Esteve and Bial and personal fees from Sanofi outside the submitted work. Vineet Punia, Kai Michael Schubert, Ingrid Berg, Yan Wang, Mira Katan, Giovanni Merlino, Piergiogio Lochner: nothing to disclose.